Method of locating special transposition-points.



. H. MOURADIAN. METHOD 0F LOCATING SPECIAL TRANSPOSITION POINTS.

APPLICATlON FILED .lAN.v2. |917.

Patented June 5,1917

HUEES M if si TELMIELOMJE AND TELEGRAPH COMPANY Tllti @F NEW YORK.

Application led January 2,

To aZZ whom t may concern:

' Be it known that I, HUGHES MOURADIAN, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain Improvements in Methods of Locating Special Transposition- `Points', of which the following is a specifiand vertical distances betweenthe disturbing conducto;l and the signaling circuit. -To obviate this diiiculty, it has been customary to introduce special transpositions in the regular sections the points being determined by a consideration of the average variation in spacing between the conductors over sub-A sections of the full sections. This, however, is not a suiiciently exact procedure togive always satisfactory results. The present invention provides a method readlly carried out in the field whereby the intermediate transposition points are located with such accuracy that substantial neutralization of the disturbances, especially those due to electrostatic induction, is obtained. More generically, it consists in determining at a plurality of transposition points the changes in the electrical characteristics of the disturbed circuit necessary to effect an approximate neutralization ofthe disturbances, and locating the desired transposition at a point Xed by the character of such changes.

In the accompanying drawing, Figure 1 illustrates diagrammatically one full transposition section of a signaling circuit to which my improved invention `may be applied; and Fig. 2 shows schematically the principle upon which the invention is based.

Ordinarily the volume of current 'flowing over high tension conductors is so small that the chief eEect on adjacent signaling circuits is electrostatic. For a transposition section of a signaling circuit, as that indicated at A between the poles 10 and .Q1-in Fig. 1, the mutual capacity e'ects between the two conductors L and L thereof and the We 0F LCATING SPECIAL TRANSPOSITIDN-POINTS.

Specification of Letters Patent.

EMV, F PHILADELPHIA, PENNSYLVANIA, ASSIGNOR, T0 AMERICAN 0F BDSTGN, MASSACHUSETTS, A. CORPORA- Patented J une .5, igt

1917. serialno. 140,245.

high tension conductor Zis as represented in Fig. 2, there being capacities C and C between Z and L and L respectively, and capacities C2 and C3 between the last-named conductors and ground. This, it will be seen, forms a VVheatstone balance, the arms of which are furnished by the 4four capacities just enumerated, while a connection between the lines L and L provides the bridge conductor L". vIt will be evident that if the product of the capacities C and C equals the product of the capacities C2 and C3, the potentials; at the bridge terminals will be equal andl no disturbing current will flow in the signaling circuit. Further it is apparent that this' condition may' readily be obtained by the introduction of artificial capacities or condensers between the conductors L, and

ground. This relation is taken advantage of in the performance of the present method in the following manner:

Considering the signaling circuit, as illustrated in Fig. l, the conductors are carried by poles l() to 2l, inclusive, the transposition's :tor the regular section A thereof being shown at the first and last of these poles. If no special transpositions have already been cut in for the purpose of remedying disturbances producedby the varying positions of the conductor Z with relation to the conductors L and L along the section, tentative transpositions are made at poles 13 and 19, these points appearing from inspection to be the ones best suited for the purpose. There being still disturbance in the signaling circuit, as shown by listening at a' high impedance'receiver R bridged across the conductors L and L at pole 13, a variable condenser c is connected between the conductor L and ground, a suflicient capacity being introduced by a condenser c between conductor L and ground to neutralize any constant lcapacity which may exist in c. The section A being preferably opened at ,the extremities during the test to isolate it from adjacent sections, condenser c is adjusted until, upon listening at the receiver R, which by virtue of its connection across thejcircuit occupies a position in the bridge conductor Lo of the Wheatstone, balance, as illustrated in Fig.

2, the sounds due to induction from the conductor Z are minimized. The tentative transposition is then moved to an adjacent,

pole, as 14, and a like test made. These 'two capacity values, and the relationl between the points of application to the signaling line L with respect to direction and distance, furnish means for determining the location of the transposition which will resultin neutralization of the disturbance without the use of artificial capacity. For

example, in a case in practice it was found that in the first test an introduced capacity of 300 microfarads was required to give a balance of potential, while for the second a capacity of 610 microfarads was necessary. Thev distance between lthese transposition poles being. 148 feet, it appeared that for each foot the transposition point wasshifted the disturbing' effect was increased to an extent' demanding 21 microfarads for its neutralization. It'was obvious from this that to obtain neutralization by the trans' position, the separation of the high tension conductor from the conductors under test being substantially constant over that portion of the section A in which'the test was being conductedit must be moved from pole 13 in a direction opposite from pole 14, and that the movement in feet must equal the capacity in microfarads (300) employed to obtain a balance at the first tentative transposition divided by the number of microfarads (2.1) which balanced a foot of movement of the transposition lpoint. In the case under consideration, it was found that by transposing L and L at a distance of 143 feet from pole 13 in a location at 12 near the pole 12 there was attained substantial freedom from disturbance in the signalin gr circuit.

Vhen the sourceI of disturbance is metallic circuit or a multi-phase circuit, the simple Wheatstone balance relation hereinbefore pointed out dqes not strictly apply,

so that absolute Vneutralization will not result from an application of this method. It will, however, serve to determine a point of minimum disturbance.

I claim:

1. The method of locating transpositionv points in signaling circuits to overcome disturbances from adjacent conductors which consists in. determining changes in the electricalcharacteristics of the circuit necessary to effect a substantial neutralization of the.disturbances for a plurality of transpositions, and making the desired transposition at a point fixed by the nature of' the changes in such electrical characteristics.

The vmethod of determining special transposition points in signaling circuits to overcome inductive disturbances from adjacent conductors which consists in tentatively transposing the circuit, determining- 

